DESCRIPTION: (Applicant's Abstract) The current administrative structure has enabled the development of the center into a highly productive and visible national resource in just three years. The accomplishments of the current center include 22 published articles and book chapters in both substantive and methodological outlets; one book published and another in active preparation; a special issue of a journal; 23 articles or book chapters submitted or in active preparation; 29 technical reports; six major statistical software programs; and 103 presentations and posters in national and international settings, including 24 at the Society for Prevention Research. In addition, we estimate over 500 researchers have attended our conferences and workshops, including a major scientific conference on analysis of longitudinal data, three Summer Institutes on Longitudinal Methods, two workshops at the Society for Prevention Research meetings, and numerous other workshops and short courses. The Administration; Training, and Development Core of the proposed center builds on and improves upon the strengths of the current center. This core has the important charge of shepherding the scientific progress and productivity of the center, forming an External Advisory Committee to help keep the center true to its original mission, and instituting effective administrative procedures. A vital function of this core is maintaining an infrastructure for collaboration not only among the Investigators, but also between the Investigators and prevention scientists outside the center. This collaboration essential to our center because it will ensure that the center remains effective both at identifying the critical issues in prevention methodology and placing the solutions to these problems in the hands of prevention scientists. Another important objective of this core concerns training, mentoring, and career development, in particular providing seed and pilot funding that will help give junior researchers the resources they need to develop careers in prevention methodology .